Method and apparatus for multiple blow molding with rotary turntable

ABSTRACT

A method and apparatus are provided for multiple simultaneous blow molding operations for forming hollow objects such as containers, the method and apparatus employing at least two circumferentially spaced parison forming means with a single rotary indexing turntable. A first container is formed at one station and a second container is formed at about the same time at a second station circumferentially spaced from the first station, and the containers are simultaneously circumferentially transferred to an unloading station. The method and apparatus provide for multiple container forming and unloading operations on the same turntable. Different containers may be manufactured at the same time with one rotary indexing turntable.

This is a division application of application Ser. No. 368,249, filedJune 8, 1973, now U.S. Pat. No. 3,854,855, issued Dec. 17, 1974.

This invention relates to blow molding. Specifically this inventionrelates to manufacturing plastic containers, such as bottles wherein aparison is extruded between opposed parted mold cavities and then blownin the closed mold to final configuration by the use of internallyapplied air pressure. More specifically this invention relates tomanufacturing plastic containers as aforesaid wherein multiplemanufacturing operations are performed with a single rotary turntable.

Heretofore one extruder was employed to extrude a parison forpositioning in an opened partible mold mounted on a rotary indexingturntable. The mold was then closed and the parison was formed into acontainer. During one rotation of the turntable the blow moldedcontainer was formed, cooled and discharged from the reopened mold,prior to the reopened mold being positioned to receive the next extrudedparison. In the prior art, the container discharge station was generallythat indexing station next preceding the extruder station. The reopened,emptied mold was thus transferred from the discharge or unloadingstation to the extruder station.

Attempts were made to increase production rates by increasing therotational speed of a conventional size turntable. Such attempts howeverwere of limited success as the increased angular accelerationnecessitated turntable redesign which was thought to be prohibitive.

It has now been found that many thermoplastic materials could beextruded, blow molded to form a hollow object such as a container, andthe formed container unloaded from a rotary turntable by utilizing lessthan about one-half the full rotation of a conventional size turntableat customary rotational speeds.

It has now been further found that a blow molded container may bedischarged from an opened mold at an extruder station just prior to thesame opened mold receiving a parison from the extruder station, withoutany significant increase in the extruder station indexed dwell period.

Now therefore there is provided by this invention a method and apparatusfor multiple extrusions and blow molding operations with a single rotaryindexing turntable thereby increasing rates of production heretoforeunattainable for such turntable.

It is therefore an object of this invention to provide a method andapparatus for multiple blow molding operations to be performed with arotary indexing turntable.

It is a further object of this invention to provide a method andapparatus as aforesaid wherein at least two extruders arecircumfrentially spaced adjacent a rotary indexing turntable forproviding parisons at about the same time to separate molds.

It is still a further object of this invention to provide a method andapparatus as aforesaid wherein multiple parison positioning operationsare actuated simultaneously.

It is still a further object of this invention to provide a method andapparatus as aforesaid wherein several different objects may be blowmolded at about the same time on a rotary indexing turntable.

It is still a further object of this invention to provide a method andapparatus as aforesaid wherein the unloading of a blow molded objectfrom the mold is accomplished at an extrusion station just prior to thepositioning of a parison therewithin.

Another object of this invention is to provide a method and apparatusfor loading a parison into and unloading a blow molded object from anopened partible mold with minimum dwell time.

It is a further object of this invention to provide a method andapparatus for loading a parison and unloading a blow molded object asaforesaid wherein multiple loadings and unloadings are performed atabout the same time with a rotary indexing turntable.

It is a further object of this invention to provide an apparatus forunloading a blow molded object from a partible mold as aforesaid whereinthe apparatus is mounted to partible sections of the mold and iscooperatively actuated with the opening of the mold.

Another object of this invention is to provide a method and apparatusfor multiple blow molding with a rotary indexing turntable which is safeand practical in use and yet such apparatus is readily fabricated and ofrelatively inexpensive construction and practical in design andoperation.

Further objects and advantages of the present invention will becomeapparent from the following description and the accompanying drawingswhich illustrate certain presently preferred embodiments of theinvention and wherein:

FIG. 1 is a top plan schematic view of the rotary indexing turntable andextruder stations of this invention;

FIG. 2 is a side elevational schematic view of the apparatus of FIG. 1depicting mold A and D at stations I and IV respectively;

FIG. 3 is a side elevational view of the parison loading apparatus takenalong line 3--3 of FIG. 1;

FIG. 4 is a side elevational view of mold D at station IV, depicting inaction sequence container unloading and parison loading operations;

FIG. 5 is a side elevational view of mold A in partial sectional view,at station I, immediately upon closure of the mold;

FIG. 6 is a functional schematic of the apparatus of this invention;

FIG. 7 is an enlarged side elevational view of the container unloader;and

FIG. 8 is a partial sectional view taken along line 8--8 of FIG. 3.

Referring now to FIGS. 1 and 2, there is shown a rotary indexingturntable 10 having six equiangularly spaced partible molds A through Fmounted thereon. Each of the molds A-F is rotatably indexed, inseriatim, that is, each mold is sequentially stopped in rotation of theturntable 10, at each of six equiangularly circumfrentially spacedstations I through VI, in the counter-clockwise direction as viewed inFIG. 1. A first thermoplastic extruder 11a is operatively positioned atstation I and a second thermoplastic extruder 11b is operativelypositioned at station IV, diametrically disposed 180° from the firstextruder. The said extruders 11a and 11b are mechanically equivalent inoperation.

Each thermoplastic extruder 11a, 11b is generally of conventional designand comprises heated thermoplastic material plasticizer portions 12a,12b respectively; extruder screw drive portions 13a, 13b respectively;cross-head die assemblies 14a, 14b respectively; outlet dies 15a, 15brespectively; and respective die faces 16a and 16b. Thermoplastic pelletmaterial feed systems including thermoplastic material hopper and dryerassemblies are provided for each extruder and are of conventionalconstruction and operation (not shown).

Both extruders 11a and 11b are operated at the same rate of production,and the extruder screw shaft (not shown) for each is rotated at the samerate. In the specific preferred embodiment described herein, thirtyturns of each screw extruder shaft are completed for each 360° rotationor one full turn of turntable 10. Every five turns of each screwextruder expresses sufficient plasticized thermoplastic material fromits respective die face to form a parison P of sufficient length to formblown object O. Said parison P after being formed is then served fromits respective die face, grabbed, lowered and positioned between aparted, opened, indexed mold, as will be more fully describedhereinafter. Each parison P is then blow molded in the closed mold toform an object O, such as a container or bottle.

The screw extruder shaft of extruder 11a is mechanically interconnectedthrough belts and pulleys 17 to the input end 18a of reducing coupling18. At the output end 18b of reducing coupling 18, there is mounted acam 19. Every five turns of the screw extruder input shaft results inone rotation of cam 19. In each rotation of cam 19, micro switch E-154is actuated. Each rotation of cam 19 constitutes one indexing cycle ateach station I and IV.

In the following discussion the parison loader apparatus of station I isdenoted by the suffix a, in contradistinction to the parison loaderapparatus of station IV wherein the equivalent apparatus features aredenoted by the suffix b.

Micro-switch E-154 is electrically connected to parison loaders 20a and20b for extruders 11a and 11b respectively. The parison loaders 20a and20b are mechanically equivalent. The function of the parison loaders isto sever the parison P from the respective die faces 16a and 16b, grabor pinch the parison at the top severed end and then lower the parisonso as to position the parison between parted halves of an opened mold.

Referring now specifically to FIGS. 3 and 8 there is shown parisonloader 20a. A tubular support frame 21a supports a cantilevered topflange member 22a, cantilevered intermediate flange member 23a and acantilevered bottom flange member 24a. Flange members 23a and 24a aregenerally of the same configuration and are in opposed facingrelationship. Supportedly mounted between cantilevered intermediateflange 23a is a vertically disposed pneumatic cylinder 25a. Aretractably extensible ram 26a is slidably received in the bottom end27a of cylinder 25a. End face 27a of parison loader 25a is mounted tothe top face 28a of flange 23a. An upper portion 29a of cylinder 25a ismounted through hole 30a of the bottom part of flange member 22a, andretained therein. A pneumatic hose 32a, through connection 32a, issecured to the top end of cylinder 25a. A compressed air feed line forcylinder 25a generally shown as 33a is mounted to frame support 21a andcomprises a filter 34a, a pressure gauge 35a and pressure reducing valve36a, and a lubricator 37a.

As stated a retractably extensible ram 26a is in sliding engagement withthe bottom 27a of pneumatic cylinder 25a. A guide fixture 38a dependsfrom and is mounted to vertical depending portion 39 a of flange 23a, bymeans of bolts 40a (typical). Stop member 41a is fixedly mounted at anintermediate portion of ram 26a and contactingly engages the lower face42a of guide fixture 38a. Member 41a is in turn disconnectably fixed inplace by nut 42a. Ram 26a passes through parison lowering member 44abeing held in place by means of nuts 43a and 50a. Parison loweringmember 44a is provided with two vertically disposed through holes 45aand 46a for sliding engagement with two vertically disposed spaced rods48a and 49a respectively. The top and bottom ends of each of the rods48a and 49a are securely mounted to flanges 23a and 24a respectively. Abracket 51a is mounted to the side 52a of parison lowering member 44a,that is, that side of the parison loading member 44a that is in facingrelationship with the die 15a of extruder 11a. Extending outwardly frombracket 51a are two pair of spaced bracket portions 52a1, 52a2, 53a1 and53a2. A pair of double acting air cylinders 54a and 55a arehorizontally, transversely disposed to and mounted through and betweenone each of the two pair of brackets. That is one cylinder each ismounted between one of said pair of bracket portions 52a1, 52a2, 53a1and 53a2. Between and at the ends of the cylinders 54a and 55a, plates56a and 57a respectively, are fixedly mounted so as to be movable withthe retraction and extension of the rams for the cylinders 54a and 55a.A pair of facing vertically disposed angle flanges 60a and 61a are alsomounted for horizontal movement with the simultaneous double actingextension and retraction of the rams of pneumatic cylinders 54a and 55a.A pair of horizontally disposed plates or jaws 62a and 63a are mountedto respective flanges 60a and 61a, that is, one jaw for each flange. Ofcourse the flanges 60a and 61a and in turn the jaws 62a and 63a would bemoved toward and away from each other with retraction and extension bycylinders 54a and 55a.

Mounted to the top face of jaw 62a is parison severing member 80a. Theparison severing member is fixedly mounted to jaw 62a by means of bolts64a (typical). The top edge 81a of parison severing member 80a is insliding resilient relationship with die face 16a of extruder 11a.

A compressed air supply line generally shown as 70a is provided tosupply compressed air to both cylinders 54a and 55a. Compressed airsupply line 70a comprises a filter 71a, a pressure gauge 72a, reducingvalve 73a and lubricator 74a. Compressed air conduits from supply line70a to the cylinders 54a and 55a are not shown.

Referring now specifically to FIG. 8, there is shown parison P centrallyaxially located on the line of closure for jaws 62a and 63a. Edgeportions 62a1 and 63a1 of jaws 62a and 63a are in facing relationship.In the retraction of cylinders 54a and 55a, jaws 62a and 63a move towardeach other and edge portions 62a1 and 63a1 contactingly, grippinglypinch parison P. Edge portion 81a faces upwardly from face 65a of 80a soas to sever the parison P from die face 16a. The severing edge 81acompletely passes through parison P after jaw edges 62a1 and 63a 1 havesecurely, grippingly, retained the parison therebetween. Parisonsevering member 30a is provided with a cut-out 82a to prevent adheringof the top circumfrential edge of the parison after severing and also toprevent adhering of the bottom leading edge of the next formed parison(not shown). The broken line construction of FIG. 8 depicts the jaws 62aand 63a closed on the parison and in a lowered position. When cylinder25a is actuated by cam actuated micro-switch E-154, ram 26a is extendeddownwardly thereby lowering member 44a as it slidably engages rods 48aand 49a.

Micro-switch E-154 simultaneously actuates pneumatic cylinders 54a, 55aand 25a, so that as pneumatic cylinder 25a begins to lower member 44a,cylinders 54a and 55a are being retracted so as to retract or closeplates or jaws 62a and 63a on parison P. Inasmuch as the parisonlowering member 44a has a mechanical lag as compared with the quickeracting jaws 62a and 63a, the parison is severed (by severing member 80a)and grabbed (by jaws 62a and 63a) just prior to being lowered.

In lowering the parison, member 44a moves to a lowered position as shownin broken line illustration. An adjustable stop 90a is affixedly mountedto bottom flange 24a, so that upon descent of member 44a, lowerdepending end portion 75a of shaft 26a contactingly abuts protrudingshaft end portion 91a of stop 90a. The stop 90a is adjustable to insurethe proper vertical positioning of parison P in the opened mold (notshown in FIG. 3).

Further as lowering member 44a nears the end of its descent,micro-switch E-116a is contacted and actuates the closing of mold A atstation I, as will be fully discussed hereinafter. It is of courseunderstood that at about the exact same time, parison severing, grabbingand lowering operations are also being performed at station IV, so as tolower a second parison into opened mold D and similarly, micro-switchE-116b would be actuated to close the parted mold sections of mold D onsaid second parison.

Referring again to FIGS. 1 and 2, the rotary turntable, generally shownas 10 is of conventional size and generally of conventional constructionwith certain modifications as will be discussed hereinafter. Theturntable 10 is driven by a standard 10 h.p. motor 100 which isconnected through belts and pulleys generally shown as 101 to clutch 102actuatable by clutch valve SV-108. The clutch 102 is a M)7S Posidyne,manufactured by Force Control Industries, Hamilton, Ohio. A master camE-106 for the rotary turntable is mounted adjacent to the drive motor100 and is operatively connected to clutch solenoid valve SV-108. Themaster cam is an Allen Bradley Bulletin 803, Style E, Model 9Emanufactured by Allen Bradley Co., Milwaukee, Wis. The master cam E-106comprises nine distinct limit switchs, LSW1 through LSW9 inclusive;L.S.W.'s 1, 2, 4 and 7 not being utilized for the particular embodimentof the invention as described herein. Each of the operable L.S.W.'s aredesigned so as to be actuated during particular times during rotation ofthe turntable for the sequential timing of the several blow moldingoperations.

When the clutch 102 is engaged the driver motor drives circumfrentialgear 105 which in turn engages the circumfrental gear 106 of turntableso as to cause rotation of the turntable in the counter-clockwisedirection as viewed in FIG. 1. Thusly, mold A moves from station I tostation II and mold E moves from station II to station III, and soforth.

A cylindrical support column 110 is axially disposed to rotary turntable10 and is mounted to base frame 107 of rotary turntable 10. Supportcolumn 110 is provided with connection for compressed air and water forperforming blow molding operations for each mold, in the conventionalmanner. At the upper end of support column 110 is a commutator 111 whichmaintains electrical connection from the master cam E-106 to and fromthe parison loaders 20a and 20b and the several molds, as the turntableis rotated.

Referring now specifically to FIG. 4, there is shown mold assembly D inthe opened position at station IV, although it is of course to beunderstood that this opened mold disposition is typical of each mold ateither station I or station IV. It is also of course understood that allof the molds have corresponding features and each of the suffixes A-Ddenote a particular mold.

Mold assembly D comprises a vertically disposed inner support frame 112Dand a spaced, opposing, facing, vertically disposed, outer support frame113D. Frames 112D and 113D are fixedly mounted to member 114D which inturn is mounted to frame 107. Four horizontally disposed, spaced moldsupport rods 115D, 116D, 117D and 118D are transversely fixedly mountedto and between support frames 112D and 113D by means of nuts 119D(typical). Two sections 120D and 121D of partible mold D are slidablymounted on support rods 115D, 116D, 117D and 118D. The mold sections120D and 121D are disconnectably connected to brackets 122D and 123Drespectively. One end 124D of linkage assembly 125D is fixedly securedto bracket 122D and the other end 126D of linkage assembly 125D isfixedly secured to member 127D. Member 127D is formed with four throughholes 128D, 129D, 130D and 131D for sliding engagement with support rods115D, 116D, 117D and 118D, respectively. Four mold close rods 132D,133D, 134D and 135D are fixed secured at one end of each thereof tomember 127D by means of nuts 136D and 137D (typical). The otherrespective ends of rods 132D-135D inclusive are secured to bracket 123Dby means of caps 138D, 139D, 140D and 141D, respectively.

Linkage 125D comprises a series of linkage 142D, 142D' and 143D; linkage142D at one end being pivotally connected to bracket 127D and at theother end being pivotally connected to linkage 142D'; linkage 142D' inturn is rotatably mounted on shaft 144D and the other end of linkage142D' is pivotally connected to linkage 143D; and linkage 143D is inturn pivotally connected to bracket 122D. A drive linkage assembly 150Dis mounted to the pivotal connection of linkages 142 and 143 and saidlinkage assembly is fixedly mounted to vertically disposed retractablyextensible ram 151D of pneumatic cylinder 152D.

By this manner of construction mold D is opened by the actuation ofsolenoid valve SV-117D to deliver compressed air to cylinder 152D tocause the vertical extension of ram 151D causing the upward movement ofdrive linkage 150D which in turn causes counter-clockwise rotation ofpivotal connections of linkages 142D' and 143D, and 142D and 142D' aboutshaft 144D. This linkage rotation results in mold section 120D andmember 127D being drawn closer in sliding on support rods 115D-118D,inclusive. Mold section 121D is concommitantly moved away from itscounterpart sections 120D by the reaction of member 127D pushing rods132D-135D, inclusive. To close the mold D, solenoid valve SV-117D isactuated to deliver compressed air to cylinder 152D to cause thedownward retraction of ram 151 which in turn causes the downwardmovement of drive linkage 150D which in turn results in the clockwiserotation of the aforesaid pivotal connections. The linkages 141D, 142D'and 143D are thusly extended causing mold section 120D and 121D to closeat a pre-calculated centerline disposed below the axis of the parison Pat station IV.

In FIG. 5, mold A is depicted as having just been closed on a loweredparison. The linkages 141A, 142A and 143A are shown extendedhorizontally. The rotational direction arrows about shaft 144A atstation I are corresponding opposite to those of shaft 144D at stationIV.

Coolant fluid such as water is supplied to and returned from the moldsthrough piping 160. Compressed air is supplied through a common rotaryconnection (not numbered) and is separated into two air feed systems towit; the mold open-close air supply system, generally shown as 161, andthe parison blow molding air supply stem, generally shown as 162. Themold open-close air supply system supplies compressed air to pneumaticcylinders 152A-152D. The parison blow molding air supply system suppliescompressed air to blow pipe assemblies 170A-170D.

Each blow pipe assembly 170 (A-D) is of usual design, such as by way ofexample the blow mold cylinder described in U.S. Pat. No. 3,334,773. Theblow pipe assembly pierces the parison enclosed in the mold and thenintroduces compressed air to the interior of the parison so as to causethe parison to expand to conform to the interior of the moldconfiguration, thereby forming a blown object O such as a container andthe like. In FIG. 5, mold A is enclosed on parison P and is pinching theparison, the lower end thereof is pinched and sealed so as to formbottom flash F1 and the top end of the parison pinch to form top flashF2. The parison P in FIG. 5 is thus ready for the introduction ofcompressed air.

It is also noted in FIG. 5 that in closing mold sections 120A and 121A,two corresponding sections 181a and 182A, respectively, of containerunloader assembly 180A are closed about parison flash F2.

In FIG. 7 the solid line drawing depicts the closed mold section with aparison or object therewithin. The broken line drawing depicts thecontainer unloader 180 with the mold sections pushed away from oneanother.

Unloader assembly 180 (typical of A-D) comprises a pair of opposedfacing symmetrical sections 181 and 182. The following discussion isgenerally limited to section 182 but it is of course understood thatcorresponding features are found in section 181. Each section comprisesa mounting base, as 301 fixedly secured to a respective neck portion ofthe mold section 120 (typical A-D). Spaced above and in facingrelationship to the base is a top 303. Sides 305 and 307 enclose the top303 and base 301. Side 307 is shown for section 181. A bushing 308fixedly secured between the bottom face of top 303 and the top face ofbase 301. A rod 311 is slidably received through bushing 308 of section182, and rod 312 is slidably received through bushing 306 of section181. Rod extension member 313 is fixed to post 315 of rod 311 by meansof pin 316.

A washer 317 is mounted to end face 318 of rod extension member 313 bymeans of a spherical headed bolt 319. Bolt 319 is secured to extensionmember 313 by means of pin 320. The outer face, that of washer 319 is incontacing relationship with end 322 of bushing 308 when the mold isclosed.

The spherically-shaped end 319 is off-set from the axis of the rod. Thisspherical shaped surface pressing contacts the parison top flash portionF2. That is the opposed facing spherically headed bolts pinch theparison as the mold is closed on the lowered parison. In FIG. 7, P isshown in pinched construction. The opposed bolts 319 and its counterpartare in horizontal axial alignment. The spherical ends of bolt 319 andits counterpart push the top flash of the parison along a line aboutcoaxial with the center of gravity of the object. This coaxial alignmentassures that the object O will fall free straight down without cockingin a direction because of imbalance, when released by the unloader.

Rod 311 is attached by nut 332 to retractably extensible ram 330 ofpneumatic cylinder 331. A compression spring 333 is housed in aircylinder 331 so as to bias the rods away from the center-line of themeeting line at which the molds close. The compression spring force isfrom about 5 to about 20 pounds and is readily overcome by the action ofthe closing molds which pull the rods 311 and 312 towards each other.

The other end of pneumatic cylinder 331 is formed with a flange 336having transverse through hole. Said through hole is coaxial withthrough hole 337 of upright flange 338. A second upright flange 339having a coaxial hole is mounted on the other side of cylinder flange336. A pin 340 passes through the aforesaid holes so as to provide apivot for cylinder 331. Flanges 339 and 338 are bolted to plate 341 bybolts 342 (typical) which plate 341 in turn is welded to and bolted tovertical mold frame support 112 (typical A-D). The opposing air cylinder335 is likewise pivoted and bolted to opposing mold frame support 113(typical A-D).

A three-way valved air limit switch AL-135 is fixedly mounted to theinward face of mold frame support 113 (typical A-D). The switch AL-135is constructed and positioned so that upon opening of the mold (A-D),mold section bracket 123 (A-D) trips the switch as the opened moldclears the major sectional dismension of the container O.

Container O is of course being held in place between the unloader rodsunder a force exerted by compressed air to the inlet sides of cylinders331 and 335. The compressed air being supplied from the air sourceinterconnected to SV-117. That is as the signal to open the mold isprovided by LSW3 (cam E-106) the actuation of SV-117 (A-D) providescompressed air not only to open the mold but to prime the unloadercylinders as well. In this manner, container O remains in place as themold is opened.

Switch AL-135 interconnects a compressed air supply line 350 which isinterconnected from a tap line from SV-117 (A-D) and then to the inletsides or pressurization sides of each of unloader cylinder 331 and 335,respectively, through lines 351 and 356. Switch AL-135, on its outeroutlet side is interconnected to the outlet side or depressurizationside of each of the unloader cylinders 331 and 335 through lines 352 and353, respectively. In this manner of construction, as switch AL-135 isactuated, the compressed air lines 351 and 350 are closed so as todiscontinue the pressurization of cylinder 335 and 331, and thecompressed air in the cylinders is expelled through lines 352 and 353 tothe atmosphere.

As the compressed air is expelled from unloader cylinders 331 and 335,compression springs 33 in cylinder 331 and its counterpart in cylinder335 drive the rods 312 and its counterpart 311 away from the containerO, thereby permitting the container to fall free clear of the part moldsections 120 (A-D) and 121 (A-D). The container falls into hopper 360(typical A-D) for conveyance to the trim and finishing operations (notshown).

The afore-described apparatus is operated in the manner as hereinafterdescribed with particular reference being made to FIG. 6.

In FIG. 6, the functional schematic of the apparatus is simplified toshow molds A and D at stations I and IV, respectively. It is of courseunderstood that diametric molds B and E, and C and F could similarly berepresented.

In FIG. 6, and referred to herein, the numbers in brackets refer to theparticular circuit under discussion.

The screw extruders 11a and 11b are turned "on" to operatesimultaneously at identical rates of production. For each and every fiveturns or rotations of the extruder screw 11a, cam 19 undergoes a singlerotation closing switch E-154, closing the circuit through the normallyclosed contacts 200 of master coil R1 (mounted on master panel, notshown). In closing switch E-154, solenoid valves SV-120a, SV-120b areactuated, permitting compressed air to cylinders 25a and 25b, therebycausing parison loaders 20a and 20b, respectively, to be lowered (201and 202). Concommitantly, the same closing of switch E-154 actuatessolenoid valves SV-119a and SV-119b permitting air to cylinders 54a, 55aand 54b, 55b respectively, thereby causing the closing (203 and 204) ofjaws 62a, 63a and 62b, 63b, respectively so as to grab and sever parisonat stations I and IV respectively. As stated insofar as the jaws 62a,63a and 62b, 63b are quicker acting than lowering members 44a and 44b,the parisons P are first severed and grabbed before actually beinglowered.

As parison loaders 20a and 20b are nearing the end of their descent,member 45a and 45b, trip micro-switches E-116a and E-116b, respectivelyclosing the circuits (205 and 206), respectively, so as to actuate therespective mold closing solenoids SV-117A an SV-117D (207 and 208). Thecircuit connections from the micro-switches E-116a and E-116b to themold solenoid valves SV-117D are made through brush (typical) and slipring (typical) of commutator 11 (typical).

As molds A and D close, respectively, mold sections 121A and 121D tripswitches E-112A and E-112B closing the blow air on circuits (209 and210), to cause the expansion of the parisons. The closing of circuits(209, 210) also energizes relay R1 and switch E-118, so that R1 normallyopen contacts 211, close solenoids SV-119A, D and SV-120A, D to causethe parison loaders 20a and 20b to return to their upper positions(circuits 212, 213), and concommitantly to open the parison grippingjaws (62a, 63a, and 62b, 63b), as by circuits (214, 215). Further theclosing of normally open contacts 211 of relay R1, clutch solenoid valveSV-108 is energized through table cam limit switch LSW9 of master tablecam E-106.

The energizing of clutch solenoid valve SV-108 causes engagement ofclutch 102 to start rotation of the turnable.

As the molds rotate 60° , limit switchs LSW5 and LSW6 actuate theclosing of the circuit to shut blow air off to the molds (B and E forthe case at point) that are next approaching stations I and IV. Uponsomewhat further rotation before indexing, limit switch LSW3 closes andenergizes solenoid valve SV-117F and SV-117E so as to open the mold topermit unloading of bottles and to institute another indexing cycle.

In FIG. 6, the schematic diagram shown for molds A and D only andtherefore limit switches LSW5 and LSW6 will actuate SV-111A and SV-111Dto shut off the blow air at about the end of the third index cycle, thatis when mold A reaches station IV and mold D reaches station I, at 180°rotation. These operations are of course repeated so that each mold A-Dis unloaded and reloaded twice for each 360° rotation of the turntable.

In actuality LSW5 and LSW6 are interconnected through a jump switchE-125 at commutator 111. So that in one index cycle LSW6 of cam E-106will actuate the air "off" to both molds A and D and in the next indexcycle LSW5 of cam E-106 will actuate the air off to both molds B and E.That is each limit switch, LSW5 or LSW 6 is actuated during eachalternate index cycle. Since there are six molds for a 360° rotation,each limit switch LSW5 or LSW6, is actuated every other 60° rotationperiod of the turntable 10.

Also near the termination of each index cycle LSW8 is actuated to assistcommutator 111 in the load switching so as to prolong the useful life ofcommutator 111.

During discharge of the containers from the respective molds, asaforesaid, and as the molds are entering the respective extruderstations I and IV, LSW9 of cam E-106 actuates SV-108 to disengage clutch102 causing the turntable to stop. That is to say the mold comes to acomplete stop to discharge the container and immediately thereafterreceive the next formed parison which is being lowered into the nowopened and unloaded mold. (See action sequence of FIG. 4). Thiscombination of parison loading and container unloading as the turntableis indexed, minimizes the dwell time at the extruder stations.

Since each mold undergoes bottle unloading and parison loading twice foreach rotation, production rates can in theory be doubled that ofconventional systems.

Furthermore, while the molds A-D are shown as being identical in thepreferred embodiment this need not be the case and it is within the thecontemplation of this invention to produce at least two differentproducts simultaneously with a single rotary turntable. Further thethermoplastic material at each extruder, e.g. 11a and 11b, need not bethe same but may vary in polymer structure or certain physicalproperties such as color. Therefore it is also within the contemplationof this invention to simultaneously produce at least two products ofdifferent polymers and/or color with a single rotary turntable.

It is within the contemplation of this invention that the means to forma parison comprise a thermoplastic extruder and die operativelypositioned at a station. Further it is also within the contemplation ofthis invention that means to form a parison comprise a single extruderwith means to convey the extruded mass to at least two separate dies,wherein each of the dies being operatively positioned at first andsecond stations circumfrentially spaced one from the other. In otherwords while it may be desirable, it is not necessary to provide separateextruders at each station whereat a parison is to be formed. Moltenthermoplastic material may be conveyed to parison forming dies at anydesired station or number of stations. Therefore the terms "means toform a parison" is defined herein as including the immediately aforesaidarrangement of a single extruder with separate remote die means as wellas the heretofore described preferred embodiment.

Further it is also within the contemplation of this invention to havemore than two extruder stations in operation so as to further increasethe production rates. Also of course more than one parison may be formedat each extruder station and several containers may be blow moldedsimultaneously at each mold assembly.

As can be seen the above description discloses a method and apparatusfor producing hollow plastic articles such as containers atsubstantially higher rates of production than was previously heretoforepossible with a rotary indexing turntable.

From the foregoing description of the invention, it will be apparentthat various modifications in the method and apparatus described indetail herein, may be made without departing from the spirit and scopeof the invention and it is not intended that the invention be limited tothe specific embodiment shown herein, but is to be construed accordingto the appended claims.

What is claimed is:
 1. A blow molding apparatus comprising a rotaryindexing turntable, means to rotatably index the turntable to apredetermined number of circumfrentially spaced stations, said turntablehaving at least one partible mold mounted therewith for each of saidcircumfrentially spaced stations, means to provide opened molds at atleast at first and second of said spaced stations, first means to form afirst parison operatively positioned at said first station and secondmeans to form a second parison operatively positioned at said secondstation circumfrentially spaced from said first station, said first andsecond parisons being formed at about the same time, means to positionsaid first parison and means to position said second parison between theparted sections of each of the respective molds at the respective firstand second stations, means to close said opened molds on said formed andpositioned parisons at the respective first and second stations, firstmeans and second means to introduce air under pressure to the interiorof each of the respective parisons to expand the parisons to conform tothe interior of the respective molds so as to form hollow objectstherein, means to cool each of said objects during rotation of theturntable and circumfrential transfer of the molds from at least saidrespective first and second stations, and means for removing the formedobjects from the opened molds, at at least one of the said first andsecond stations so as to permit other formed parisons to be positionedtherebetween.
 2. The blow molding apparatus of claim 1, wherein thefirst parison forming means and the second parison forming means arediametrically disposed and fixedly disposed at said first and secondstations respectively.
 3. The blow molding apparatus of claim 1, whereineach of said means for removing the formed object comprises means tohold at least a portion of the object in opening the mold and means torelease said held portion so as to permit said object to fall free ofthe parted opened mold.
 4. The blow molding apparatus of claim 3,wherein each of said holding means comprises a pair of opposed spacedmembers, and means to advance said members toward each other uponclosure of the mold so as to contactingly hold the upper flash portionof the parison therebetween.
 5. The blow molding apparatus of claim 4,wherein each of said releasing means comprises means to retract saidmembers one from the other upon clearance of the opened mold from theformed object held therebetween, so as to permit said object to fallfree of the parted mold.
 6. The blow molding apparatus of claim 1,wherein said first parison forming means comprises a first extruder andfirst die means and wherein said second parison forming means comprisesa second extruder and second die means, said die means being spaced fromrespective molds, and wherein said rate of first extrusion is aboutequal to the rate of said second extrusion.
 7. The blow moldingapparatus of claim 6, further comprising means to interconnect the firstextruder to each of said means to position said parisons between therespective opened molds, so as to simultaneously position and first andsecond parisons.
 8. A blow molding apparatus comprising a rotaryindexing turntable, means to rotatably index the turntable at apredetermined number of circumfrentially spaced stations, said turntablehaving at least one partible mold mounted therewith for each of firstand second spaced stations, means to provide opened molds at said firstand second stations, first means to form a first parison operativelypositioned at said first station and second means to form a secondparison operatively positioned at said second station circumfrentiallyspaced from said first station, said first and second parison beingformed at about the same time, means to position said first parison andmeans to position said second parison between the parted sections ofeach of the respective molds at the respective first and secondstations, means to close said opened molds on said formed and positionedparisons at the respective first and second stations, first means andsecond means to introduce air under pressure to the interior of each ofthe respective parisons to expand the parisons to conform to theinterior of the respective molds so as to form hollow objects therein,means to cool each of said objects during rotation of the turntable andcircumfrential transfer of the molds from said respective first andsecond stations, and means for removing the formed objects from theopened molds so as to permit other formed parisons to be positionedtherebetween, wherein each of said means for removing the formed objectcomprises means to hold at least a portion of the object in opening themold and means to release said held portion so as to permit said objectto fall free of the parted opened mold, further comprising means tomount each of said object removing means on respective parts of thepartible mold.
 9. The blow molding apparatus of claim 8, wherein each ofsaid means to hold said parisons comprises, a pair of retractablyextended rod members being in end face opposition, said end faceportions contactingly holding a portion of the object therebetween, eachof said rod members being mounted to and slidable relative to arespective part of the partible mold, and said releasing means comprisesmeans to retract said extended rod members to permit said object to fallfree clear of the opened mold.
 10. The blow molding apparatus of claim9, wherein each of said objects comprises a container and wherein saidend face portions contactingly engage a portion of the object above theneck of the container and about coaxial with the largest circumfrence ofthe container.
 11. The blow molding apparatus of claim 2, furthercomprising an even-numbered plurality of partible molds mounted on saidtable and being equi-angularly, circumfrentially spaced, one mold eachat one each of said stations, and wherein said first parison formingmeans comprises a first extruder and first die means and wherein saidsecond parison forming means comprises a second extruder and second diemeans.
 12. The apparatus of claim 1, wherein said first parison is ofone thermoplastic material formed from a first extruder and wherein thesecond parison is of a second thermoplastic material formed from asecond extruder.
 13. A blow molding apparatus comprising a rotaryindexing turntable, means to rotatably index the turntable at apredetermined number of circumfrentially spaced stations, said turntablehaving at least one partible mold mounted therewith for each of firstand second indexing stations, means to provide opened molds at saidfirst and second stations, means to form a first parison to beoperatively positioned at said first station and to form a secondparison to be operatively positioned at said second stationcircumfrentially spaced from said first station, means to position saidfirst parison and means to position said second parison between theparted sections of each of the respective molds at the respective firstand second stations, means to close said opened molds on said formedpositioned parisons at the respective first and second stations, meansto introduce air under pressure to the interior of each of therespective parisons to expand the parisons to conform to the interior ofthe respective molds so as to form hollow objects therein, means to cooleach of said objects during rotation of the turntable and circumfrentialtransfer of the molds from said respective first and second stations,and means for removing the formed objects from the opened molds at atleast one of the first and second stations so as to permit otherparisons to be positioned therebetween.
 14. The blow molding apparatusof claim 13, said means for removing the objects, comprising oneremoving means each being mounted above the respective mold andcomprising means to hold the top flash portion of the parison from whichsaid object is formed, and means to release said held portion so as topermit said object to fall free of the parted mold.
 15. The blow moldingapparatus of claim 13, wherein said first and second parison formingmeans are fixedly disposed at said first and second stationsrespectively.
 16. The blow molding apparatus of claim 15, wherein saidfirst and second stations are diametrically disposed and wherein themold at said first station is transferred to said second station whilesaid mold at said second station is simultaneously transferred to saidfirst station in horizontal rotation of the turntable.
 17. The blowmolding apparatus of claim 13, wherein each of the parison forming meansoperates continuously and simultaneously, and wherein each of saidparison positioning means operates intermittently and simultaneouslywith the other parison positioning means at respective stations.
 18. Theblow molding apparatus of claim 17, wherein there are means to removethe object at the respective stations each of which operate at about thesame time as the means to position said parisons, at said respectivestations.
 19. The blow molding apparatus of claim 1, wherein each ofsaid parison forming means continuously and simultaneously extrudeparisons, and wherein each of said parison positioning means operatesintermittently and simultaneously with the other parison positioningmeans at respective stations, and wherein there are means to remove theobject at the respective stations each of which operate at about thesame time as the means to position said parisons at said respectivestations.